The present invention relates to a power transistor device and more specifically to a technology suitably applied to a so-called IC igniter, an ignition apparatus of internal combustion engines.
In a conventional ignition device (IC igniter) of a multi-cylinder internal combustion engine mounted in automobiles, a Zener diode (transformer) is provided between collector and base of a bipolar transistor making up a power transistor device used in the IC igniter to stabilize a voltage of a primary coil to be applied to each cylinder. A Zener voltage of the Zener diode stabilizes a reverse voltage produced in the primary coil. Such a power transistor device uses a Darlington transistor circuit. Japanese Patent Publication No. 51256-1990, corresponding to U.S. Pat. No. 4,618,875, discloses a power transistor device using the Darlington transistor circuit.
U.S. Pat. No. 5,115,369 discloses a JFET having a clamping polycrystalline silicon diode. U.S. Pat. Nos. 4,013,904 and 4,293,868 disclose a Zener diode connected between base and collector of an input transistor of a Darlington type. U.S. Pat. Nos. 4,928,053 and 5,079,608 describe a diode and a Zener diode connected between gate and drain of a power transistor. U.S. Pat. No. 5,025,298 discloses a back-to-back polycrystalline silicon diode coupled to a gate of a power TMOS device. U.S. Pat. No. 5,136,348 describes a technology to form a polycrystalline silicon P-N junction in a form of a ring.
U.S. Pat. No. 5,204,988 discloses a polycrystalline silicon bi-directional Zener diode coupled between gate and source of a MOS semiconductor device. The bi-directional Zener diode is formed ring-shaped at the circumference of a chip.
Japanese Patent Laid-Open Nos. 202,867/1989, 87,873/1983, 84,461/1983 and 111,363/1992 disclose a technology to form a polycrystalline silicon diode connected between gate and source of FET in a form of a ring at the circumference of a chip.
Japanese patent Laid-Open No. 185,069/1990, corresponding to U.S. Ser. No. 278,988, discloses a back-to-back polycrystalline silicon diode connected between gate and drain of IGBT.
Japanese Patent Laid-Open No. 38,881/1991 discloses polycrystalline silicon bi-directional Zener diodes connected between gate and source and between gate and drain of an insulated-gate field-effect transistor.
Japanese Patent Laid-Open No. 211,293/1993 discloses a MOSFET and a polycrystalline silicon Zener diode.
Japanese Patent Laid-Open Nos. 218,437/1993, 192,170/1990, 139,766/1992 and 234,173/1992 disclose a polycrystalline silicon diode coupled between gate and source of a MOSFET.